Image forming apparatuses includes printers, facsimile machines, and copiers, for example.
Ink jet image forming apparatuses (ink jet recording apparatuses) are known as a kind of image forming apparatus. The ink jet recording apparatus records images on a recording medium such as paper and transparent plastic sheets for OHP, by discharging ink droplets from a recording head thereof. The advantages of the ink jet recording apparatus include low running cost, low noise, and easy color printing using multiple color inks.
Electrophotography image forming apparatuses are known as another kind of image forming apparatus. The electrophotography image forming apparatus forms toner images on a photosensitive unit using a charging unit, an exposure unit, and development unit, for example; transfers the toner images on the recording medium using a transfer unit; and fixes the transferred toner images using a fixing unit.
Japanese Patent Laid-Open Application No. 11-151841 discloses a conventional image forming apparatus in which a paper cassette is loaded from the front of the image forming apparatus and paper is fed from the rear of the image forming apparatus. After an image is formed on the paper, the paper is discharged into a paper discharge tray at the rear of the image forming apparatus. In another conventional image forming apparatus, paper is fed from a paper feed tray loaded at the rear of the image forming apparatus, and the paper is discharged into the paper discharge tray at the front of the image forming apparatus.
Such image forming apparatuses are widely used both in small offices and at home where space for the image forming apparatus is limited. The image forming apparatus may be disposed on a desk or in a rack.
According to the limitation of the space, the image forming apparatus is preferably made compact. Contradictorily, the top face of the image forming apparatus is preferably made wide and flat so that a user can place something thereon.
However, if the top face of the image forming apparatus is simply made wide and flat, the top face may give a negative visual impression to the user. If the top face of the image forming apparatus is simply made wide, the loading of the paper feed tray and the handling of paper discharged into the paper discharge tray may become difficult. The operability of the image forming apparatus may be degraded. Otherwise, the paper discharge tray and/or the paper feed tray may greatly protrude from the image forming apparatus body. The footprint of the image forming apparatus may be increased.
If operations keys and displays are provided on the top face, it becomes difficult to use the top face effectively, even if the top face is made large. Additionally, if the top face of the image forming apparatus body is made flat, the user can place something thereon. However, it is not cost-effective to design the image forming apparatus body to support heavy weight.
As described above, the footprint of the image forming apparatus is preferably small. However, if paper is fed from the rear and discharged to the front of the image forming apparatus, even if the image forming apparatus body is made compact, the total system becomes considerably larger. It would be difficult to dispose it on a desk or in a rack.
In the case of the conventional image forming apparatus disclosed in the above Japanese Patent Laid-Open Application No. 11-151841 in which the paper feed tray and the paper discharge tray are disposed at the same side, its total space may become small. However, the paper feed tray (paper cassette) needs to be loaded from the opposite direction in which paper is fed. Accordingly, a large space is required in front of and in rear of the image forming apparatus so as to handle (load and remove) the paper feed cassette. It is difficult to dispose the image forming apparatus on a desk or in a rack.
According to the above problems, it is preferred that the paper feed tray be loaded at the front of the image forming apparatus, and the paper be fed from the lower front, reversed in the image forming apparatus, and discharged to the upper front of the image forming apparatus. In this case, the paper feed tray is positioned under the paper discharge tray. It becomes difficult to handle the paper feed tray while replenishing with paper.
If the total height of the image forming apparatus needs to be reduced, the paper needs to be reversed at a short radius in the image forming apparatus, especially in the case of the ink jet recording apparatus. The paper discharge tray needs to be disposed to some extent below the opening through which paper is discharged so that a large amount of paper can be stacked in the paper discharge tray. In addition, it is effective to transport paper to its width direction to make the depth of the image forming apparatus short and to make the speed of print operation fast.
However, if paper is reversed at a short radius, the paper tends to roll up in the transport directions, which may make the discharging of the paper difficult. Likewise, if the paper discharge tray is disposed below the opening to some extent, the paper drops in the paper discharge tray with its top rolled up due to its weight, which makes the discharging of the paper difficult. The forming of images on paper using ink droplets makes the paper easily roll up. The rolling up of the paper may be increased by the effect of the direction of fibers forming the paper.
Furthermore, it is desired that not only the feeding and discharging of paper but also the ink cartridges, power switch, connection with the PC, and power cable, for example, be accessible from the front in order to improve the operability of the image forming apparatus.
It is also preferable that accessories such as a manual, a USB cable, preparative inks, and installation disks be stored in the image forming apparatus so as to avoid losing them.